code: def test_multi(self):
      c = Cumulative()
      c.extend([2, 3], [4, 6])
      c.append(1)
      assert_allclose(c.get_buffer()[0], torch.tensor([2, 3, 1]))
      assert_allclose(c.get_buffer()[1], torch.tensor([4, 6]))
  
      c.reset()
      c.append()
      c.extend()
      self.assertEqual(c.get_buffer(), [])
      c.get_buffer().append(1)
      self.assertEqual(
          c.get_buffer(), []
      )  # no in-place update for the buffer
  
      c.reset()
  
file_path: MONAI/tests/test_cumulative.py
imports: from __future__ import annotations
  import unittest
  import torch
  from monai.metrics import Cumulative
  from tests.utils import assert_allclose
label_desc: Use image node_id 2 for calling the TestCumulative obj's underlying member method code with example usage: obj.test_multi() without return types